As used herein, a ceramic frit is a ceramic composition in a powdered or granulated state. The ceramic may be a glass. Ceramic frits are conventionally obtained from the mixing of raw materials such as feldspars (which supply Na2O, K2O and SiO2), barium oxide (BaO), strontium oxide (SrO), and sodium oxide (Na2O). The raw materials are then fused in a furnace and rapidly quenched in water. Frit compositions can be varied according to the quantities and types of oxides desired in their formulation. Frits are used mostly in the vitrifying of flooring, glazed ceramics and other ceramic products. Frits can also be used in enameling of Iron or Steel.
Several strategies have been proposed for recycling of Cathode Ray Tubes (CRTs). CRTs typically include several different types of glass. The glass of the panel portion of the CRT is predominately SiO2 and often includes BaO and SrO. The glass of the funnel portion of the CRT is also predominately SiO2 and often has a higher PbO content than the panel glass. Table 1 gives chemical composition ranges of panel and funnel glass for CRTs (Hreglich, S. et al. 2001, “The recycling of end of life panel glass from TV sets in glass fibers and ceramic productions”. In: Dhir, K. et al. (eds) Recycling and reuse of glass cullet, Thomas Telford Publishing, London, p. 126); traces (less than 1%) of LiO2, ZnO, As2O3, TiO2, F and CeO2 may also present.
TABLE 1Wt%PanelFunnelSiO259.0-64.550.30-63.80Al2O31.75-3.651.1-5.0Na2O5.15-9.455.3-8.3K2O6.0-8.5 6.1-10.3CaO0.05-4.351.05-4.45MgO 0.1-1.750.5-3.0BaO 2.2-13.90.05-3.7 SrO 0.2-11.60.08-1.0 PbO0.0-2.811.0-23.6ZrO20.0-3.50.0-0.5
Incorporation of CRT panel glass into a ceramic glaze formulation has been reported (Andreola et al., 2007, “Recycling of EOL CRT Glass into Ceramic Glaze Formulations and Its Environmental Impact by LCA Approach”, Int J LCA, 12 (6) 448-454). The standard glaze formulation was stated to contain 35 wt % of glassy frit in combination with other raw materials such as clays and feldspars. Modification of this composition by substitution of 30 wt % of this frit by panel glass was reported.